El Nino - Animation of warm pool

• El Nino refers to the eastward movement of warm water (shaded red) from the western equatorial pacific to the eastern equatorial pacific.
• The animation of sea surface temperature (SST) anomalies to the right shows the unusual warming that occurred during the 97-98 event.
• Note that an anomaly is a departure from some "normal" value.  An anomaly can be either positive (warm) or negative (cold)